Natural Events

By Jack MacRae

Here’s what’s debuting on nature’s stage in Chicago Wilderness

Early Winter

Racks Off

At some point this winter, our bucks will run out of mojo and their antlers will fall off. It happens every year. For a male white-tailed deer, decreasing hours of sunlight trigger their pineal gland to alter the production of certain hormones, including testosterone. Antlers are secondary sex characters profoundly affected by hormones. The bucks will shed them after the level of testosterone dwindles away during January and February.

No Yoke?

Hop hornbeams are common little trees (30 to 40 feet) that grow in the understory of our woodlands. They can be identified in winter by their brown, flaky bark and their distinctive fruit — a small, tan, leafy sac that holds a cluster of small nutlets. The fruit of the hop hornbeam bears a resemblance to the hops of beer-making fame. In merry old England, a horn-beam was a stout piece of lumber used to connect teams of oxen, draped and secured across their shoulders and horns. With white, dense wood that is amazingly strong and difficult to split, hornbeam trees acquired their name from this apparatus.

Middle Winter

Crust Fungus

Next time you’re enjoying your favorite oak woodland, take note of the wide, pale gray bands of smooth bark on the tree trunks. I grew up calling them cow rubs, but perhaps that was just my family’s term. The marks are actually made by Aleurodiscus oakesii, a saprophytic (lives off dead things) crust fungus that is actively decomposing the rough, non-living outer layer of bark. Don’t worry about the tree. Despite the appearance, there is no internal decay and the trees aren’t damaged by this minor plant pathogen. The fungus is most apparent on white oaks, but it can be found on other tree species.

Pink

Don’t be overly alarmed if you notice pink urine stains on the snow. Hare pee comes in many hues. Pigments found in eastern cottontail urine produce a color range of yellow to pink to red to deep orange. Our rabbits need to be extra wary on the snow. Unlike many of their hare cousins, eastern cottontails do not turn white for the winter and cannot rely on disruptive coloration for security purposes.

Late Winter

Red-Bellied Rappers

Naturally designed and intelligently described, male red-bellied woodpeckers do have a small, pink tummy. It’s just hard to see; they’re usually pressing their belly against a tree trunk. In late days of winter, red-bellied woodpeckers become highly conspicuous in the woodlands, flashing their colors as they swoop from tree to tree. Their backs and wings are zebra-striped. The nape of the lovely female’s neck is brilliant scarlet. The male has a similar colored stripe leading from the crown of his head down his neck. Red-bellied woodpeckers show excitement by raising these neck feathers.

Woodpecker boys and girls aren’t interested in each other during the darker days of January and February. But as the end of winter nears, their interest in the opposite sex is renewed. Courting activities seem to commence in late February and continue for a month or more. Part of the pairing ritual is the duet-style tapping, with couples rapping out rhythms to each other with their bills. Red-bellies are seasonally monogamous, and researchers believe that drumming and tapping helps maintain bonds.

Hot Wax

Our waxwings are styling! They’re sleek, silky, and wear a black Lone Ranger-style mask outlined in white. The secondary feathers on their wings appear to have been dipped in red candle wax and the tip of their tail feathers has a canary yellow band. They have a jaunty crest. Cedar waxwings feel as soft at they look.

Waxwings are frugivores; their bodies are specialized for a diet of sweet, high-sugar fruits. During the winter, flocks of 10 to 30 cedar waxwings roam the Chicago Wilderness, eagerly plucking cherries from the trees in our forest preserves and parks.